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Model 8902A
Operation
4.
Verifj. that the Automatic Cal-Factor table was entered correctly.
Recall the reference cal factor and compare the value to that on the label on the power sensor:
37.5 SPCL,
%
CAL FACTOR (Blue Key,
MHz)
5. Recall each frequency/cal-factor pair and compare each value to its counterpart o n the power
sensor:
37.6 SPCL;
DISPLAY FREQ (Blue Key,
fi)
to display the frequency value,
%
CAL FACTOR (Blue Key, MHz) to display the cal factor value.
Repeat this step until
all
frequency/cal-factor
pairs
have been verified.
0
Attempting to read beyond the end of the table results in Error 26.
0
To replace an existing cal-factor entry, enter the new cal factor at the frequency previously
used in the entry (refer to step 1).
0
To remove an existing cal factor from the table in memory, enter 0% as the cal factor at the
frequency previously used in the entry (refer to step 1).
6. To re-enter the Automatic Cal Factor mode, select AUTOMATIC OPERATION, then reselect
RF
POWER.
Zero the Sensor.
Ifthe instrument has just been turned on, allow at least a half-hour continuous
op-
eration. Connect the sensor between the Measuring Receiver's SENSOR input and CALIBRATION
RF
POWER OUTPUT.
7. Select ZERO.
J f a power sensor
is
being used (rather than a sensor module) the CALIBRATE
key light must be off for proper zeroing. (A sensor module has an internal switch that will
automatically switch out
any
input signal.) After a few seconds, 0.0 00 W is displayed, then a
measurement result of near zero power is displayed.
Configure the
1
mW RF
Power Reference
8. Select CALIBRATE. The instrument
displays
the power from the
RF
power reference
using
the last calibration scaling.
Enable Calibration Scaling
9. Select SAVE CAL (Blue Key, CALIBRATE). Read 1.000 mW. The calibration scaling stays
in effect until another SAVE CAL operation is done. Select CALIBRATE again to turn off
the calibrator (CALIBRATE key light om .
CK
the calibrator is not turned off, the RF power
measurements will not range properly.)
THE
MEASURING
RECEIVER IS NOW CALIBRATED.
Measure power levels by selecting
RF
POWER.
(Note that when calibrating the Measuring Receiver over
HP-IB,
u s e
T3 settling time code between
the CALBRATE (C1)
and
SAVE CAL (SC) codes. For example: ClT3SC.)
Additional Recommendations:
0
Re-calibrate the sensor when ambient conditions change or approximately every eight hours.
0
Whenever the source frequency
is
changed, either select the new frequency manually
(in
MHz)
or select FREQ to let the instrument automatically tune to the signal, then re-enter the RF Power
measurement mode. Also,
if
the tuned frequency moves more that
hi5
kHz from the frequency at
which the power sensor reference was taken, the instrument must be retuned.
0
Use the table
on
the following page, ''Summaqy of Special Function
37" for a
quick overview of all
the codes that manipulate the RF power
cal
factors.
3-77
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